JP3113989B2 - Structure of electronic component substrate and heater using this structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a substrate for an electronic component and a heater using the structure, and the heater uses a toner transferred from a photosensitive drum onto a sheet in an electrophotographic process. It is suitable for use when fixing.

[0002]

2. Description of the Related Art The conductor patterns formed on the front and back surfaces of an electronic component substrate are electrically connected to each other through so-called conductor through holes to reduce the space efficiency of the circuit configuration. To improve,
This is a common practice. The above-described conductor through hole is conventionally formed by the following method.

First, as shown in FIG. 6A, a through hole b having a predetermined constant inner diameter is formed in a substrate a, and conductor patterns c and c are formed on the front side and the back side of the substrate a.
Is formed by printing and baking using a conductive paste. Next, as shown in FIG. 6B, suction is performed from the front side while supplying the conductive paste from the front side or the back side, for example, from the back side, and the conductive paste is spread over the entire inner surface of the through hole b. After that, this is fired to form the first conductor layer d in the hole.

[0006] Next, as shown in FIG. 6 (c), contrary to the above, suction is performed from the back side while supplying the conductor paste from the front side, and the above-mentioned is superimposed on the first conductor layer d in the hole. After the conductor paste is spread over the entire inner surface of the through hole b, it is fired to form the in-house second conductor layer e. This allows
The conductor patterns c, c on the front side and the back side of the substrate are:
The first and second conductor layers d and e laminated in the through hole b electrically conduct each other.

As shown in FIG. 6 (c), when forming a conductor through hole, a conductor paste is supplied into the through hole b and sucked from the opposite side of the through hole. As a result of adopting the method for coating in a through-hole, the conductor paste forms a swelling f around the hole opening on the side where the suction force is applied. For the purpose of simply electrically connecting the conductor pattern on the front surface side and the back surface side of the substrate, as shown in FIG. 6 (c), there is a swelling of the through-hole forming conductor near the opening of the through-hole b. No problem.

However, for example, in the case where another object such as paper or a sheet is used in sliding contact with a heating element formed on a substrate, such as a heater or a thermal print head, the paper or the sheet is used. The conductor through hole having the swelling f as described above cannot be formed in the area where the sheet-like material slides. This is because the swelling f as described above may damage the surface of the paper or sheet in sliding contact.

As shown in FIG. 7, the heating heater is formed by forming a band-shaped heating element h extending in the longitudinal direction on the surface of an insulating substrate g having a rectangular shape in a plan view by printing and baking. In order to drive the heat by passing a current through the belt-shaped heating element h, it is basically constituted by forming electrode terminal portions j, j so as to conduct to both ends of the belt-shaped heating element h. Such a heater is used in an electrophotographic process.
An electrophotographic process apparatus has recently begun to be used as a fixing heater for fixing a toner carrying toner transferred from a photosensitive drum onto a sheet, and can be formed as a lightweight, low-cost, thin component. In order to cope with the miniaturization, weight reduction, and cost reduction of the printer, attention has been paid as an alternative to the traditional heater that inserts a halogen lamp, which has been conventionally used as a fixing heater in this type of fixing unit. I am collecting.

In such a heater, the conductor electrode may need to be arranged on the back surface side. In such a case, the conductor through hole for that purpose has conventionally been provided outside the paper passage range. In this case, the layout of the conductor pattern is restricted, and the shape of the substrate must be relatively large.

The present invention has been conceived under the above circumstances, and has been developed to provide a structure of an electronic component substrate having a conductor through hole that does not form a raised protrusion on the substrate surface. Provide and use this structure,
It is an object of the present invention to increase the degree of freedom for forming a conductor pattern on a substrate of a heater or a thermal print head.

[0010]

Means for Solving the Problems To solve the above problems, the present invention takes the following technical means. That is, in the electronic component substrate according to claim 1 of the present application, a conductor material different from each of the above-described conductor patterns is attached to the inner surface of a through-hole formed in the substrate with the conductor pattern on the front side and the conductor pattern on the back side. An electronic component substrate electrically connected through a conductor through hole formed, wherein the through hole has a spot facing portion on the substrate surface side,
The end of the conductor material forming the conductor through hole on the substrate surface side is located in the counterbore portion.

In the heater according to the second aspect of the present invention, a strip-shaped heating element extending in the longitudinal direction is formed on the surface of the insulating substrate, and the strip-shaped heating element or a conductor electrode formed adjacent thereto is connected to the heating element. The conductor electrode formed on the back surface of the insulating substrate is electrically connected to the inner surface of the through-hole formed in the substrate through a conductor through-hole formed by attaching a conductor material different from the above-mentioned band-shaped heating element or the conductor electrode. The through hole has a counterbore on the surface side of the substrate, and an end of the conductor material forming the conductor through hole on the substrate surface side is the counterbore. It is characterized by being located inside the department.

[0012]

According to the present invention, when a conductor through hole is formed in a substrate, a through hole provided in the substrate in advance has a counterbore portion on the surface side, and a conductor through hole is formed in the counterbore portion. Is characterized in that the end of the conductive material for forming the substrate surface side is located. That is, when supplying a conductive paste for forming a conductor of a through hole from the back surface side of the through hole and applying a suction force to the front surface side to spread the conductive paste into the inside of the through hole, suction is performed. The raised portion of the conductive paste due to force or gravity, that is, the end on the substrate surface side is formed in the counterbore portion, and this raised portion can be prevented from appearing on the substrate surface.

When the conductor through hole is used to electrically connect a heating element on the front surface of the substrate or a conductor electrode electrically connected to the heating element to a conductor electrode on the rear surface of the substrate, Since it is possible to eliminate the swelling-like projections seen in the configuration of the conventional conductor through hole on the substrate surface side of the hole, it is possible to arrange such a conductor through hole without limiting the place on the substrate. it can. That is, regarding the case where the heater of the present invention is used as a fixing heater in an electrophotographic process, even in a region where a sheet on which toner is to be fixed passes, there is no problem, And the backside of the substrate. This is because the smoothness of the substrate surface is ensured despite the arrangement of the conductor through-holes. This is because the fear of hurting is wiped out.

Therefore, in the heater according to the present invention, the degree of freedom in forming conductor patterns formed on the front and back surfaces of the substrate for driving the heating element formed on the insulating substrate is greatly increased, and the size of the substrate is reduced. In addition, it is possible to realize an improvement in the function as a heater, such as an improvement in the heating element driving mode.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. The drawing shows the heater H
Shows an example in which the present invention is applied. The heater H has a rectangular strip-shaped insulating substrate 1 formed on a surface thereof with a belt-shaped heating element 2 extending in the longitudinal direction. The belt-shaped heating element 2 of the present example is a main heating element 2a that extends linearly in the longitudinal direction.
And sub-heating elements 2b, 2b which are bent in a U-shape from both ends of the main heating element 2a and extend a predetermined length inward in the longitudinal direction of the substrate. The insulating substrate 1 includes:
For example, it can be made of a ceramic plate. The heating element 2 can be easily formed by printing and baking using a resistor paste such as a silver / palladium paste.

Further, by covering the heating element 2,
A protective glass coating 4 has been applied. In the present embodiment, as described above, the reason why the sub-heating elements 2b, 2b having a double structure with respect to the main heating element 2a are formed from both ends of the main heating element 2a is that the amount of heat dissipated at the end is an intermediate part. The temperature distribution at the end of the heating element 2 is relatively lower than the temperature at the middle part because the heat dissipation amount is larger than the heat dissipation amount in the above. This is to correct the temperature and prevent the temperature of both ends of the heat generating portion from being lowered by the heat generated by the sub-heater, and to stabilize the temperature distribution over the entire length of the heat generating portion. Thus, when this heater is used in the toner fixing section of the electrophotographic process, it is possible to avoid fixing unevenness due to uneven temperature distribution.

Both ends of the heating element 2, that is, the inner ends of the sub-heating elements 2 b, 2 b in the longitudinal direction of the substrate are formed on the back surface of the insulating substrate 1 via conductor through holes 5, 5. It is electrically connected to the conductor electrode patterns 6 and 6. The back conductor patterns 6, 6 extend to the terminals 7, 7 arranged at the rear end of the substrate. As can be seen from FIG. 1, in the present embodiment, the conductor through holes 5, 5 are provided at the ends of the sub-heating elements 2b, 2b extending inward in the longitudinal direction of the substrate.
Is formed, the position of the through holes 5 and 5 is within the effective heating width L of the heating element 2, that is, inside the passage area of the sheet on which the toner is to be fixed. Therefore, a projection that damages the paper should not be formed in the substrate-shaped region L. However, in the present invention, by forming this as the following conductor through holes 5 and 5, Have achieved.

That is, as shown in detail in FIG. 2, according to the present invention, the through hole 7 provided in the insulating substrate 1 to form the conductor through holes 5 and 5 has a counterbore on the substrate surface side instead of a constant inner diameter. A through hole 7 having a portion 8 is provided. The shape of the counterbore portion 8 may be a step-down shape as shown in the example shown in FIG. 2 or a counterbore shape as shown in FIG. The through-hole 7 having such a counterbore 8 may be provided before or after the formation of the heating element 2 and the back-surface conductor electrode patterns 6 and 6 on the insulating substrate 1, but preferably, the heating element 2 and the conductor electrode pattern It is good to provide before forming 6,6.

The method of forming the conductor layer on the inner surface of the through hole 7 is the same as the conventional method. That is, first, a suction force is applied from the front side of the through-hole 7 while supplying a conductor paste different from the heating element 2 and the back electrode pattern 6 from the back side of the through-hole 7 so as to be dragged by the suction force. The conductive paste is spread over the entire through-hole 7. Then, this is fired to form the first conductor layer 9a in the hole, and then, contrary to the above, while applying the conductor paste from the front side of the through-hole 7, a suction force is applied from the back side, and The conductor paste is spread over the entire first through-hole 9a so as to overlap the first conductor layer 9a in the hole by being dragged by the suction force, and is fired to form the second conductor layer 9b in the hole. In this manner, the heating element 2 on the front side and the conductor electrode patterns 6 and 6 on the rear side are electrically connected to each other through the first and second conductor layers 9a and 9b attached and fired on the inner surface of the through hole 7. It is made conductive.

As described above, the conductive paste is sucked and spread into the through-hole 7, and as a result, the conductive paste swells at the opening of the through-hole on the suction side due to the action of the suction force. In the present invention, the counterbore portion 8 is provided on the substrate surface side of the through hole 7, so that the swell as described above is formed only in the counterbore portion 8, and a protrusion is formed on the substrate surface. There is no.

Therefore, in the case where the front surface side and the back surface side are electrically connected to each other by using the through-holes 5 and 5 configured as in the present invention, a protrusion is formed on the front surface side of the substrate due to the through-hole. Formation can be avoided. Regarding the heater of this embodiment, the heating element 2
Through-holes 5, 5 inside the effective heating width L of
However, the through through holes 5, 5
In some cases, no protrusion is formed on the substrate surface, and the substrate smoothness within the heat generation width L is ensured. Therefore, the heat generation function can be improved, for example, by adopting the planar shape of the heat generating element 2 as shown in FIG. 1 without causing a problem that the paper on which the toner is to be fixed is scratched.

Of course, the scope of the present invention is not limited to the above embodiment. The object in which the conductor through hole is to be formed is not limited to the heater as in the embodiment, and the conductor through hole according to the present invention is applied to all the substrates having a substrate surface to which a sheet-like material or the like is to be brought into sliding contact, such as a thermal print head. By adopting the configuration described above, the degree of freedom in the layout of the conductor pattern is dramatically increased, and
It can contribute to the improvement of the function of the electronic component.

As for the heater, the heating element 2 can have a special planar shape as described above. In addition, as shown in FIG. 5, one end of the linear heating element 2 is connected to the front side. Connected to the conductor electrode part 3 and the other end is a conductor through hole 5
Also, the present invention can be applied to a case in which the terminal is connected to the conductor electrode pattern 6 or the terminal 7 on the back surface through the wire. When the conductor through hole 5 having the structure of the present invention is adopted, unnecessary projections are not formed, so that even the portion where the conductor through hole 5 exists can be used as the effective heat generation range L, and the size of the substrate 1 can be reduced. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a plan view of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged sectional view taken along the line III-III of FIG. 1;

FIG. 4 is an enlarged sectional view showing another embodiment of the conductor through hole of the present invention.

FIG. 5 is a plan view of another embodiment of the present invention.

FIG. 6 is a diagram illustrating a conventional method of forming a conductor through hole and a problem.

FIG. 7 is a plan view showing an example of a general heater to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate (insulating board) 2 Heating element 3 Conductor electrode (pattern) 5 Conductor through hole 6 Backside conductor electrode (pattern) 7 Through hole 8 Counterbore

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shigeo Ota 21 Ryozaki-cho, Saiin-ku, Ukyo-ku, Kyoto Inside Rohm Co., Ltd. (56) References JP-A-2-134889 (JP, A) Jpn. , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 1/11 G03G 15/20 101 H05B 3/00 355

Claims (2)

(57) [Claims] 1. A conductor pattern on a front surface and a conductor pattern on a rear surface are formed on the inner surface of a through-hole formed in a substrate.
An electronic component substrate electrically connected to a turn through a conductor through hole formed by attaching another conductor material , wherein the through hole has a spot facing portion on the substrate surface side. Is
With the conductor material forming the conductor through hole
The substrate surface side end is located in the counterbore
A substrate for electronic components , characterized in that: 2. A belt-shaped heating element extending in the longitudinal direction is formed on the surface of an insulating substrate, and the strip-shaped heating element or a conductor electrode formed adjacent to the strip-shaped heating element is formed on a back surface of the insulating substrate . On the inner surface of the through hole formed in the substrate
Use a belt-shaped heating element or a conductor material different from the above conductor electrode.
A heater electrically connected via a conductor through hole attached thereto , wherein the through hole has a spot facing portion on the substrate surface side.
With the conductor material forming the conductor through hole
The substrate surface side end is located in the counterbore
A heater.